The problem of controlling perennial dicotyledons, more especially bindweeds, in orchards and above all in vineyards is becoming increasingly more important every year in the major tree-growing and vine-growing countries. Ever-increasing labor costs are making it more and more difficult to carry out weed control by agricultural methods, and tree growers or vine growers expect the chemical industry to provide them with the herbicidal means required for effective weed control in their vineyards and orchards.
Although a certain number of products have already been proposed, none of them has produced really satisfactory results in efforts to control the bindweeds: field bindweed (Convolvulus arvensis) and bearbine (Calysthegia sepium), which are two of the most troublesome weeds, especially in vineyards. These weeds are able to develop extremely long shoots which twine themselves around vine stocks and, subsequently, around the vine shoots and clusters. These bindweeds cause very serious damage to the vine both by robbing them of nutritional elements present in the soil and by purely mechanical action during harvesting, resulting in the loss of numerous clusters which are "stripped" of their grapes when the vine harvester gathers the cluster.
It is known that compounds belonging to the phenoxyalkane carboxylic acid family, or phytohormones, have a very good destructive effect upon bindweed. By acting through a hormonal mechanism, they migrate into the shoots of the bindweed which are deformed and then die. Unfortunately, these phytohormones are also well known for their extremely phytotoxic effect on the vine which, when brought into contact with extremely small quantities of these phytohormones, undergoes characteristic and often irreversible deformation.
The dangers of using these compounds have been repeatedly emphasized, more especially during the 6th Conference of Columa (Cannes, 8th-10th December 1971). Various authors specializing in problems of this kind have been prompted to make remarks such as "the use of 2,4-D in vine-growing would still appear to be tricky and hazardous: its effectiveness on bindweed is undoubtedly satisfactory . . . but the dangers of phytotoxicity on leaves or clusters are so great that it would be dangerous to popularize its use" (Barralis et al.: Report of the 6th Columa, page 703), and even "2,4-D . . . remains the most effective and least onerous formulation. it is also one of the most difficult to use . . . " (Agulhon et al.: Report of the 6th Columa, page 745).
This type of remark under the signature of specialists in viticulture clearly underlines the fact that it is almost impossible to use 2,4-D in arboriculture and viticulture. In addition, this type of application is not recommended by any company because the risks involved are too great.
The same phenomena and the same disadvantages are encountered in the use of compounds related to 2,4-D, such as 2,4-DP (2,4-dichlorophenoxy propionic acid) and MCPP (2-methyl-4-dhlorophenoxy propionic acid), which, despite their indisputable action on bindweed, are no longer used for the same reason.
The acids MPP, CPP and DPP are known products: the first two are described in particular in French Patent 1,313,847 (Boots) as selective herbicides for cereal crops and clover. The acid MPP is also described in the work by J. Lhoste "Les desherbants chimiques" (page 113), 1965, in which the following conclusion is reached on this compound: "It would not seem that satisfactory results can be expected from this compound".